The present invention is directed to sound abatement methods and conveyor trolleys, and, in particular, to methods and conveyor trolleys whereby a sound abating material is applied to certain areas of trolley components to reduce the noise generated by collision between two trolleys.
Power and free conveyors are made up of a power track, a free track and a number of carriers traveling along the free track. Each carrier includes leading and trailing trolleys, and the trolleys are placed on the free track and support the carrier. The power track includes a power chain that travels along the power track. Frequently, the power and free tracks are arranged adjacent to each other and in parallel. Each leading trolley may include a retractable dog which extends toward the power track and which is engageable by a pusher dog carried by the moving power chain in the power track. When the pusher dog engages the retractable dog, the trolley, and thus the carrier, is pushed by the moving power chain to travel along the free track. When the retractable dog is retracted, or otherwise disengaged from the pusher dog, the trolley loses power and stops moving.
One of the advantages of the power and free conveyors is that the conveyors allow accumulation of carriers. Power and free conveyors often include one or more accumulation sections where a number of stopped carriers are stored in a closely spaced or contacting relationship until they are needed. In order to stop and accumulate a moving carrier, the leading trolley of the moving carrier is made to collide with the trailing trolley of a downstream stopped carrier. As the two trolleys collide, the cam lever of the leading trolley of the carrier strikes the accumulation cam of the trailing trolley of another carrier, causing the cam lever to raise the retractable dog of the leading trolley. Retracting the retractable dog disengages the retractable dog from the pusher dog so that the leading trolley, and thus the moving carrier, is no longer driven by the moving power chain.
Such collisions often generate loud noises. A carrier is made of metals and metal alloys and may carry a heavy workpiece, and thus is quite heavy. Consequently, a moving carrier possesses a large mount of kinetic energy, and this energy must be dissipated in order to stop the carrier. Because the carriers and trolleys are made from metal and metal alloys, a significant amount of energy from each collision is dissipated as sound waves. Since a conveyor line may have multiple accumulation sections and a plant may have multiple conveyor lines, the noises generated by the accumulation of carriers are substantial and frequent. The noises can be unpleasant and may have adverse health effects on employees working in the vicinity of accumulation sections.
In view of the adverse effects caused by the noises, a need has developed to provide improvements in sound abatement in connection with trolley operation.
It was found that, although a significant portion of the noise is caused by the direct collision between the body of the leading trolley and the body of the trailing trolley, other contacts among trolley components may also generate noises. In many applications, a relatively large portion of the noise is generated by the contacts among components of the leading trolley and between certain components of the leading trolley and certain components of the trailing trolley. For example, a relatively large portion of the noise may be generated by the contacts between the cam lever of the leading trolley and the accumulation cam of the trailing trolley, between the cam lever and the body of the leading trolley, between the cam lever and the retractable dog of the leading trolley, between the retractable dog and the body of the leading trolley and the contact between the retractable dog and the pusher dog during the retraction of the retractable dog from the pusher dog. There contacts include both direct and sliding contacts.
It was discovered that the application of sound abating materials to the areas where these contacts take place can reduce the noise level generated during trolley collisions. These areas may include areas on the trolley components, including the trolley body, cam lever and retractable dog of the leading trolley, as well as the accumulation cam of the trailing trolley. It was also discovered that sound abating effects may be achieved by applying sound abating materials to one or more areas of trolley components where no contact takes place. The application of the sound abating materials may include attaching the materials to these areas, including coating, gluing, frictional fit, and/or filling the cavities in these areas with the sound abating materials.
The present invention provides sound abatement methods and conveyor trolleys. According to one aspect of the invention, a method includes applying a sound abating material to at least one area of at least one component of the moving trolley.
According to another aspect of the invention, a conveyor trolley according to the present invention includes a trolley body having at least one wheel for traveling in a track and at least one component cooperatively associated with the trolley body. The component has at least one area and a sound abating material applied to the area for sound abatement.
According to a further aspect of the invention, an element used in a conveyor trolley includes at least one area and a sound abating material applied to the area for sound abatement.